Jeremy Piven was back on Broadway yesterday – dragged before a tribunal of actors and producers to convince them it really was mercury poisoning that forced him to leave “Speed-the-Plow.”

In a hearing that lasted almost as long as his run in David Mamet’s play, Actors’ Equity representatives sided with Piven, seen (right) arriving at the hearing.

But the Broadway League, which represents the producers, pursued Piven’s fish tale with the bloodlust of Captain Ahab.

Under collective-bargaining rules, the panel needs to reach a unanimous decision.

After hours of arguments, the joint panel of five actors and five producers couldn’t agree whether to sanction the party-boy actor for skipping town last December midway through the play’s run.

Sources say Piven broke down several times during the hearing as he described, in great detail, his suffering while ill.

The show’s producers, who contend that Piven continued to paint the town red when he was supposed to be seriously sick, will now consider pursuing arbitration to seek restitution for the drop in box-office receipts following his departure.

The producers had hoped the union would be so outraged with Piven’s mercurial ways that its representatives would vote against him, the actor’s spokeswoman, Samantha Mast, said in a statement.

“Although the producers might have expected to receive the support of Actors’ Equity, they did not; the union sided with Mr. Piven,” Mast said.

Piven, who claims his blood-mercury level rose to five times the normal range, is virtually unhirable on Broadway today, sources said. His stage acting career sleeps with the fishes.

But he’s fighting to regain his reputation.

When the actor blamed his insatiable sushi habit and the resulting mercury poisoning for his decision to return to LA, he received little sympathy.

Mamet quipped at the time that Piven was “leaving show business to pursue a career as a thermometer.”

But Piven contends his illness was so severe, doctors told him there was a danger of a heart attack, Mast said.

“By mid-December, his symptoms had progressed to the point that he required hospitalization,” she said.

“He was forced to withdraw from the show on the instruction of his doctors.”

But sources close to the show have said that Piven was trying to get out of it long before he became ill, and he was overheard telling people backstage that the eight performances a week had left him “bored out of his mind.”

According to Mast, the producers never had Piven examined by their own doctors to counter his claims.

And although the $3.5 million production was affected by his departure, the show ended up in the black, she pointed out.